BALL SCREW & LEAD SCREW

The ball screw drive is an assembly that converts rotary motion to linear motion (or vice versa). It consists of a ball screw and a ball nut packaged as an assembly with recirculating ball bearings. The interface between the ball screw and thenut is made by ball bearings which roll in matching ball forms. With rolling elements, the ball screw drive has a very low friction coefficient and is typically greater than 90% efficient. The forces transmitted are distributed over a large number of ball bearings, giving a low relative load per ball comparatively.

The keydifferencebetween aball screwand alead screwis in the way the load is carried between the moving surfaces.
Aball screwuses recirculatingballbearings to minimize friction and maximize efficiency
while alead screwdepends on low coefficients of friction between sliding surfaces.

Even though both types of screws are mechanical linear actuators and can be used in seemingly similar situations, each project engineer needs to consider the back drive, backlash, thrust, speed, lead accuracy, and efficiency required for the mechanism.